1. Field of the Invention
The present invention relates to a numerical controller that creates a processing path based on a sequence of command points acquired from a machining program with respect to a machine tool having a plurality of driving axes including at least two straight-line axes, interpolates the path, and drives the driving axes to the interpolated position, thereby performing machining.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 10-049215 discloses a technique of approximating a path commanded as a point sequence by a straight-line path and performing machining along the straight-line path.
Japanese Patent Application Laid-Open No. 2013-171376 discloses a technique of approximating a path commanded as a point sequence by the smallest possible number of curves such that deviation from a command point is within a set threshold (tolerance) and driving a servo motor along the curves, thereby performing machining.
A technique of approximating a sequence of multiple command points covering a wide range by a straight line or a curve of which the distance from the sequence of command points is within an allowable threshold (tolerance) is called compression of a sequence of command points. With multiple command points represented by one curve, the curve corresponding to the sequence of command points covering a wide range can be created, whereby deceleration due to insufficient ability to create a machining curve of a numerical controller and interpolate the machining curve can be reduced even if the intervals in the sequence of command points are very small.
With the above-described techniques disclosed in Japanese Patent Application Laid-Open No. 10-049215 and Japanese Patent Application Laid-Open No. 2013-171376, the compression methods have direction dependence property, that is, the compression result depends on from which direction the point sequence is compressed. For this reason, the above-described techniques have a problem that when the same command is made in the reverse direction, the same compression result cannot be assured, causing an uneven path in processing using a reciprocation path.